FIG. 1 illustrates a prior art power generating system of the type manufactured by the assignee of the present invention for use in airframes which is simulated by the present invention. The power generating system 10 is comprised of a plurality of generating units 12 each of which are coupled to a power take-off (not illustrated) from an airframe propulsion engine. Each generating unit 12 is conventional and is comprised of a permanent magnet generator which generates alternating current which is rectified and applied to a wound field exciter which produces alternating current which is rectified and applied to the rotor of a three phase alternator. As indicated by the numeric designation 1 ... n associated with each generator unit, the number of generator units varies directly with the number of engines in the airframe and typically is between 2 and 4. The rotor of the three phase alternator is driven by a constant speed transmission typically contained in an integrated drive generator (IDG) (not illustrated) which converts a variable speed power take-off from the airframe propulsion engine into a constant speed shaft drive which rotates the rotor of the three phase alternator at a velocity for producing three phase 400 Hz electrical power. Each generator unit 12 has an associated generator control unit 14 which contains a programmed microprocessor for implementing various conventional control and protection functions as well as functions which are described below which are part of the present invention. Further examples of electrical generating systems for an airframe are disclosed in U.S. Pat. Nos. 4,403,292, 4,488,198 and 4,684,873 which are assigned to the assignee of the present invention.
Generator control unit 14 is conventional. The generator control unit 14 contains a relay which controls the connection of electrical power generator by the permanent magnet generator to the wound field exciter which upon disconnection disables the generator unit from generating electrical power. A generator control current transformer 16 monitors the current generated by its associated generator unit 12. The generator control unit 14 uses the information from the generator control current transformer 16 and the system average current to determine the difference in current system average. Each generator control current transformer 16 is comprised of eight different current sensing windings. A generator control breaker 18 connects the generator to the load bus 20. A bus tie breaker 24 connects the generator control breaker 18 to the system power bus 26. The bus tie breaker 24 opening and closing is controlled by first signals on line 40 and the opening and closing of the generator control breaker 18 is controlled by second signals on line 22. The generator control breaker 18 and the bus tie breaker 24 may have different implementations which are responsive to first and second levels of a single signal or to multiple signals having multiple levels. A split system breaker 28 permits division of the system power bus 26 into two parts to permit independent operation of groups of one or more generator units 12 in parallel. One or more bus control units 30 provide control over the split system breaker 28. Furthermore, each bus control unit 30 may issue commands over control lines 32 to one or more generator control units 14 over which the bus control unit exercises supervisory control to control the switching status of either or both of the generator control breaker 18 and the bus tie breaker 24. The bus control units 30 also provide additional system protection no discussed herein through communications and hardware lines not illustrated.
An electrical power generating system such as that illustrated in FIG. 1 must provide a substantial amount of dependable power under very harsh operating conditions. The electrical power generating system must have the capability to analyze its operating condition and take actions to perform in an efficient and reliable manner. It must be able to detect faults in the electrical system and react in such a manner that prevents damage to the faulted area, while maintaining the power delivered to the operational components. To implement the necessary decision capabilities, typically over 500 rules and logic equations must be defined. These rules and equations are the heart of an electrical power generating system such as that illustrated in FIG. 1.
Currently the design of aircraft electrical power generating systems is slow and time consuming. Typically, problems are found to exist after a system is partially designed or tested. Solving problems requires time which causes design time tables to slip and development costs to increase.
A need exists for a simulator which simulates the operation of an electrical power generating system including simulating a state of the elements of the electrical power generating system during generation of electrical power and a state of elements of the electrical power generating system in response to a fault condition. A simulator would permit the designer of an electrical power generating system to identify problems and propose a solution(s) to the problems prior to substantial activities having been undertaken in the design phase. As a result the efficiency of the design of an electrical power generating system would be improved by providing a simulator Representing the behavior of the electrical power generating system to be designed prior to the actual fabrication of hardware and the writing of control software.